Rock mass integrity is an important indicator for the stability classification of roadway roof, however, the current grading methods just describe from the one-dimensional angle of rock mass structure, which cannot fully reflect the integrity of the roof rock in three-dimensional. In order to overcome the limitation, the stability classification of roadway roof in fractured rock mass is studied by using blockiness as a rock mass integrity index instead of the two sub-indicators of rock mass quality RQD value and joint spacing in the conventional grading method, creating a kind of innovation especially suitable for the fractured rock mass stability classification methods called BT classification methods. According to the block percentage and block volume distribution curve, a solving process of the blockiness of the roadway roof surrounding rock in fractured rock mass is built. An AHP method is applied to determine the weights of the stability factors. The method and the standard of stability classification are constructed. Based on structure surface data and rock mass mechanical parameters of the roadway roof in four fractured rock mass experimental zones in the ore body No. 92 of Tongkeng mine, using the RMR method in the traditional classification methods and the new development method of roadway roof stability classification for each test area, two different classification results are comparatively analyzed, the results show: compared with the traditional RMR classification methods, BT method is more superior to the stability of the description, classification accuracy and safety management guidance, it can more truly and objectively reflect the fractured rock mass roadway roof stability. Research results can provide more reliable scientific basis for the condition of complex fractured rock mass of roadway roof safety classification and management.
